Crash when opening grab menu on stack

[Sparky]

In a multiplayer game, when opening the grab menu on a specific floor stack of items, the game freezes completely.  The console has the same stacktrace repeated continuously, it seems to be executing the same function multiple times per second, and continues that forever such that it locks the game up.  Stacktrace:
Dec 23, 2020 3:45:42 PM zombie.GameWindow run
SEVERE: null
java.lang.IllegalArgumentException: Comparison method violates its general contract!
        at java.util.TimSort.mergeLo(TimSort.java:777)
        at java.util.TimSort.mergeAt(TimSort.java:514)
        at java.util.TimSort.mergeCollapse(TimSort.java:441)
        at java.util.TimSort.sort(TimSort.java:245)
        at java.util.Arrays.sort(Arrays.java:1512)
        at java.util.ArrayList.sort(ArrayList.java:1454)
        at java.util.Collections.sort(Collections.java:175)
        at zombie.iso.IsoObjectPicker.ContextPick(IsoObjectPicker.java:252)
        at zombie.ui.UIManager.update(UIManager.java:1377)
        at zombie.GameWindow.logic(GameWindow.java:630)
        at zombie.GameWindow.run(GameWindow.java:1315)
        at zombie.GameWindow.maina(GameWindow.java:1091)
        at zombie.gameStates.MainScreenState.main(MainScreenState.java:184)

[Beard]

What version of the game are you playing on? Asking mainly because I haven't seen this error in build 40 yet, and you mentioned it happening "in a multiplayer game", are you playing on co-op?